long shaft outboard performance

[oldcatamount]

Can anyone tell me why a long shaft outboard motor would impede the performance of a boat with a transom built for a short shaft motor?

 

[ezmobee]

Re: long shaft outboard performance

Drag and lots of it. Even boats with properly matched motors can pick up a few miles an hour but raising the motor an inch. I can't imagine how detrimental sticking extra 4-6" in the water would be. I'd add a jackplate if you really wanted to use your long shaft on a short transom.

 

[oldcatamount]

Re: long shaft outboard performance

Thanks ezmobee! Hard to believe it would make that much difference but I certainly trust your judgement! Thanks again for the fast responce!
Mike

 

[lncoop]

Re: long shaft outboard performance

One other thing to consider; some long shafts can be converted to short shafts. The cost is usually prohibitive, but just wanted to throw that out there.

 

[ezmobee]

Re: long shaft outboard performance

Also, not sure what HP we're talking about here but if it isn't a ton, here's a homemade jackplate idea from Tashasdaddy http://forums.iboats.com/showthread.php?t=321432

 

[oldcatamount]

Re: long shaft outboard performance

I thought about converting to a short shaft but, the short drive shaft was 200 bucks, and then I need a short shift rod connection. It's a 1976 25 hp Johnson, a good motor, but not really worth the extra money it would take.

 

[ezmobee]

Re: long shaft outboard performance

1976 25 hp Johnson

I'd absolutely go the homemade jackplate route for that motor.

 

[H20Rat]

Re: long shaft outboard performance

just a rough guess, it depends A LOT on the boat, but having 4-6 extra inches of metal in the water is going to cost you at least 20% of your horsepower, with INCREASED fuel consumption. The smaller the boat the more pronounced your loss will be.